Generally, a coating agent, which is used as an interior or exterior material of a kitchen utensil, requires excellent alkali resistance, acid resistance, wear resistance, durability, heat resistance and the like. Therefore, a fluorine resin or a silicon resin is used as a main component of the coating agent.
Here, the fluorine resin is a coating agent including polytetrafluoroethylene (PTFE), which is well known for its use in Teflon coating, as a main component. Referring to conventional technologies related to this fluorine resin, Korean Patent Registration No. 10-0099134 discloses a fluoro resin coating composition used in flow coating, comprising a blend of PTFE and a perfluorovinyl ether copolymer, an acrylate resin, and a nonionic surfactant.
When a kitchen utensil is coated with this fluorine resin, there are advantages in that the durability, corrosion resistance and the like of the kitchen utensil are improved, and food does not adhere to the kitchen utensil (that is, the kitchen utensil has non-adhesivity), but there is a problem in that, when the kitchen utensil coated with the fluorine resin is heated, volatile organic compounds (VOC), particularly perfluorooctanoate (PFOA), are generated from PTFE, and thus the generated VOCs injure a human's health when they are introduced into the human body. Further, a heat-resistant coating agent including a silicon resin is also problematic in that heat resistance cannot be exhibited at a temperature of more than 300° C., and in that the kitchen utensil coated with this coating agent is easily worn and discolored because the coating agent has low hardness.
In order to solve the above problems, Korean Utility Model Registration No. 20-0403258 discloses a ceramic glass frying pan coated with ceramic on which a ceramic coating layer is formed to improve heat resistance and durability. However, even in this case, there is also a problem in that the non-stick property of the ceramic coating layer is much lower than PTFE. Therefore, in order to solve this problem, a method of increasing non-adhesivity by mixing fluorosilane, silicon oil or the like in a top coating layer has been attempted, but this method is also problematic in that the performance of the top coating layer rapidly deteriorates because the material mixed in the top coating layer is pyrolyzed at a temperature of 260° C. or more at the time of heating, and in that the non-adhesivity of the top coating layer is easily lost because the durability and heat resistance of the top coating layer is decreased.
Therefore, the present inventors have made many attempts to solve the above problems occurring in the prior art. As one attempt, they mixed hexagonal boron nitride (hBN) and a binder for coating, coated a kitchen utensil with the mixture, and then cured the kitchen utensil. As a result, they developed a coating composition having excellent properties, which does not generate harmful gases at the time of heating, which can maintain material properties such as corrosion resistance, heat resistance, durability and the like for a long period of time because it has high hardness, and which can exhibit non-adhesivity even at a high temperature of 400° C. or more. Based on the development of the coating composition, the present invention was completed.